DNA (Double Strand) Antibody IFA

Anti-dsDNA detects autoantibodies against double-stranded (native) DNA. The IFA (indirect immunofluorescence) method uses Crithidia luciliae, a protozoan whose kinetoplast contains pure double-stranded DNA without bound proteins — providing a highly specific substrate. Positive samples show fluorescence of the kinetoplast under the microscope, and the titre is reported as the highest dilution at which fluorescence is still visible (1:10, 1:40, 1:160…).

Anti-dsDNA is one of the most disease-specific autoantibodies in rheumatology — present in 60–70% of SLE patients but rare in other conditions, making a strongly positive result highly suggestive of lupus.

Anti-dsDNA is a primary laboratory criterion for SLE in both the 2019 ACR/EULAR classification and the older ACR criteria. Beyond diagnosis, it has two unique uses: it tracks disease activity (titres often rise before clinical flares, fall with treatment), and high titres are particularly associated with lupus nephritis — kidney involvement that affects up to half of Indian SLE patients and is a leading cause of long-term morbidity.

In Indian rheumatology practice, anti-dsDNA is ordered whenever a positive ANA suggests possible lupus. Rising titres in a known SLE patient prompt closer monitoring and sometimes preemptive treatment adjustment. Falling titres alongside falling C3/C4 complement levels (with rising anti-dsDNA = active disease) and proteinuria are key signals for lupus nephritis flare.

No fasting required. Continue all medications including immunosuppressants and hydroxychloroquine — these may lower antibody levels but should not be stopped before testing without medical advice.